1. Field of the Invention
This invention relates to improvements in photographic system cameras and more particularly, it relates to a bayonet-type coupling arrangement for system cameras having quick-change, bayonet-mount interchangeable lenses.
2. Description of the Prior Art
The term `system camera`, refers to a camera that is part of a family or series of cameras, emanating from a basic design or concept, which undergoes changes from one particular camera model to the next, with successive models in the course of time.
In a system camera various components may be changed over the course of time, such as, for example, the light meter, the shutter system, the housing configuration, as well as other like components and sub-assemblies. On the other hand, major sub-assemblies such as, for example, interchangeable lenses, remain substantially unchanged from one model to the next.
Under these circumstances it is a justifiable market demand that a new camera model, immediately succeeding a predecessor model, should be adapted to accept the lens or objective assembly of the older camera model.
While such a demand from one model to the next in a series is justified, the interchangeability requirement becomes an undue burden as the number of models in the series is increased. Thus, the overall technical advancement of the system camera becomes restricted since a camera designer is limited by the interchangeability requirement. Nevertheless, periodically, parts of the objective or lenses have to be redesigned, such as, for example, the lens mounts. Such a change becomes a consideration when converting a particular model from an external light meter to an internal light meter, particularly a through-the-lens (TTL) light meter.